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Python Python Collections (2016, retired 2019) Lists Removing items from a list

Posted by Trace Harris
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Trace Harris
Python Web Development Techdegree Graduate 22,065 Points

trying to loop through an list and remove items that are not a number

So in this exercise I am trying to compare each item in messy_list to whether it is an integer or not I am trying isinstance(<var>,int) to execute my comparisons. Then if the statement is falsey I am using the .remove method remove the non integer I understand that I can remove use the .remove method three, separate times however I am trying this method for dry purposes. it seems more elegant. Error I am getting is Bummer looks like you have more items to remove from the "list". so I feel like I am on the right track just missing a piece.

lists.py 
messy_list = ["a", 2, 3, 1, False, [1, 2, 3]]

# Your code goes below here
messy_list.insert(0, messy_list.pop(3))
for item in messy_list:
    if isinstance(item, int) is False:
        messy_list.remove(item)

1 Answer

Alex Koumparos
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Alex Koumparos
Python Development Techdegree Student 36,887 Points
Alex Koumparos
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points

Hi Trace,

For the approach you want to take, you should use type() instead of isinstance(). isinstance() returns True if the tested object is of the specified type or is a subclass of the specified type. Bool is a subclass of int so when you check isinstance() for ints, that False element in the array is going to be treated as an int. The type() function, in contrast, returns the exact type of the tested object. So you can write something like:

type(x) == type(7)

And you will only get back True if x's type is the same as 7's type (which, of course is int).

Hope that clears everything up for you.

Cheers

Alex

Trace Harris
.a{fill-rule:evenodd;}techdegree seal-36
Trace Harris
Python Web Development Techdegree Graduate 22,065 Points

that makes complete sense! that clears up a lot